[PATCH net v2 0/2] net: macb: Fix two lock warnings when WOL is used

[PATCH net v2 0/2] net: macb: Fix two lock warnings when WOL is used

[Kevin Hao]

Hi,

This patch series addresses two lock warnings that occur when using WOL as a
wakeup source on my AMD ZynqMP board.

---
Cc: Nicolas Ferre <nicolas.ferre@microchip.com>
Cc: Claudiu Beznea <claudiu.beznea@tuxon.dev>
Cc: Andrew Lunn <andrew+netdev@lunn.ch>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Vineeth Karumanchi <vineeth.karumanchi@amd.com>
Cc: Harini Katakam <harini.katakam@amd.com>
Cc: Théo Lebrun <theo.lebrun@bootlin.com>

---
Changes in v2:

- Add Reviewed-by from Théo Lebrun for patch 1

- Reduce the scope of the RCU lock by using a local variable, as suggested by Théo Lebrun.

- Fix minor typos in the patch 2 subject and commit log

- Link to v1: https://lore.kernel.org/r/20260315-macb-irq-v1-0-0154104cbf61@gmail.com

---
Kevin Hao (2):
      net: macb: Move devm_{free,request}_irq() out of spin lock area
      net: macb: Protect access to net_device::ip_ptr with RCU lock

 drivers/net/ethernet/cadence/macb_main.c | 37 ++++++++++++++++++++------------
 1 file changed, 23 insertions(+), 14 deletions(-)
---
base-commit: 8e5a478b6d6a5bb0a3d52147862b15e4d826af19
change-id: 20260311-macb-irq-39b8a3333bd8

Best regards,
-- 
Kevin Hao <haokexin@gmail.com>

[PATCH net v2 1/2] net: macb: Move devm_{free,request}_irq() out of spin lock area

[Kevin Hao]

The devm_free_irq() and devm_request_irq() functions should not be
executed in an atomic context.

During device suspend, all userspace processes and most kernel threads
are frozen. Additionally, we flush all tx/rx status, disable all macb
interrupts, and halt rx operations. Therefore, it is safe to split the
region protected by bp->lock into two independent sections, allowing
devm_free_irq() and devm_request_irq() to run in a non-atomic context.
This modification resolves the following lockdep warning:
  BUG: sleeping function called from invalid context at kernel/locking/mutex.c:591
  in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 501, name: rtcwake
  preempt_count: 1, expected: 0
  RCU nest depth: 1, expected: 0
  7 locks held by rtcwake/501:
   #0: ffff0008038c3408 (sb_writers#5){.+.+}-{0:0}, at: vfs_write+0xf8/0x368
   #1: ffff0008049a5e88 (&of->mutex#2){+.+.}-{4:4}, at: kernfs_fop_write_iter+0xbc/0x1c8
   #2: ffff00080098d588 (kn->active#70){.+.+}-{0:0}, at: kernfs_fop_write_iter+0xcc/0x1c8
   #3: ffff800081c84888 (system_transition_mutex){+.+.}-{4:4}, at: pm_suspend+0x1ec/0x290
   #4: ffff0008009ba0f8 (&dev->mutex){....}-{4:4}, at: device_suspend+0x118/0x4f0
   #5: ffff800081d00458 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire+0x4/0x48
   #6: ffff0008031fb9e0 (&bp->lock){-.-.}-{3:3}, at: macb_suspend+0x144/0x558
  irq event stamp: 8682
  hardirqs last  enabled at (8681): [<ffff8000813c7d7c>] _raw_spin_unlock_irqrestore+0x44/0x88
  hardirqs last disabled at (8682): [<ffff8000813c7b58>] _raw_spin_lock_irqsave+0x38/0x98
  softirqs last  enabled at (7322): [<ffff8000800f1b4c>] handle_softirqs+0x52c/0x588
  softirqs last disabled at (7317): [<ffff800080010310>] __do_softirq+0x20/0x2c
  CPU: 1 UID: 0 PID: 501 Comm: rtcwake Not tainted 7.0.0-rc3-next-20260310-yocto-standard+ #125 PREEMPT
  Hardware name: ZynqMP ZCU102 Rev1.1 (DT)
  Call trace:
   show_stack+0x24/0x38 (C)
   __dump_stack+0x28/0x38
   dump_stack_lvl+0x64/0x88
   dump_stack+0x18/0x24
   __might_resched+0x200/0x218
   __might_sleep+0x38/0x98
   __mutex_lock_common+0x7c/0x1378
   mutex_lock_nested+0x38/0x50
   free_irq+0x68/0x2b0
   devm_irq_release+0x24/0x38
   devres_release+0x40/0x80
   devm_free_irq+0x48/0x88
   macb_suspend+0x298/0x558
   device_suspend+0x218/0x4f0
   dpm_suspend+0x244/0x3a0
   dpm_suspend_start+0x50/0x78
   suspend_devices_and_enter+0xec/0x560
   pm_suspend+0x194/0x290
   state_store+0x110/0x158
   kobj_attr_store+0x1c/0x30
   sysfs_kf_write+0xa8/0xd0
   kernfs_fop_write_iter+0x11c/0x1c8
   vfs_write+0x248/0x368
   ksys_write+0x7c/0xf8
   __arm64_sys_write+0x28/0x40
   invoke_syscall+0x4c/0xe8
   el0_svc_common+0x98/0xf0
   do_el0_svc+0x28/0x40
   el0_svc+0x54/0x1e0
   el0t_64_sync_handler+0x84/0x130
   el0t_64_sync+0x198/0x1a0

Fixes: 558e35ccfe95 ("net: macb: WoL support for GEM type of Ethernet controller")
Cc: stable@vger.kernel.org
Reviewed-by: Théo Lebrun <theo.lebrun@bootlin.com>
Signed-off-by: Kevin Hao <haokexin@gmail.com>
---
 drivers/net/ethernet/cadence/macb_main.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
index 36ab3b7e1feabd295be35152f0b464bba6fcbe18..2d4304331e297accd91ab48813a9bd4722ce72dc 100644
--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c
@@ -5968,6 +5968,7 @@ static int __maybe_unused macb_suspend(struct device *dev)
 			/* write IP address into register */
 			tmp |= MACB_BFEXT(IP, be32_to_cpu(ifa->ifa_local));
 		}
+		spin_unlock_irqrestore(&bp->lock, flags);
 
 		/* Change interrupt handler and
 		 * Enable WoL IRQ on queue 0
@@ -5980,11 +5981,12 @@ static int __maybe_unused macb_suspend(struct device *dev)
 				dev_err(dev,
 					"Unable to request IRQ %d (error %d)\n",
 					bp->queues[0].irq, err);
-				spin_unlock_irqrestore(&bp->lock, flags);
 				return err;
 			}
+			spin_lock_irqsave(&bp->lock, flags);
 			queue_writel(bp->queues, IER, GEM_BIT(WOL));
 			gem_writel(bp, WOL, tmp);
+			spin_unlock_irqrestore(&bp->lock, flags);
 		} else {
 			err = devm_request_irq(dev, bp->queues[0].irq, macb_wol_interrupt,
 					       IRQF_SHARED, netdev->name, bp->queues);
@@ -5992,13 +5994,13 @@ static int __maybe_unused macb_suspend(struct device *dev)
 				dev_err(dev,
 					"Unable to request IRQ %d (error %d)\n",
 					bp->queues[0].irq, err);
-				spin_unlock_irqrestore(&bp->lock, flags);
 				return err;
 			}
+			spin_lock_irqsave(&bp->lock, flags);
 			queue_writel(bp->queues, IER, MACB_BIT(WOL));
 			macb_writel(bp, WOL, tmp);
+			spin_unlock_irqrestore(&bp->lock, flags);
 		}
-		spin_unlock_irqrestore(&bp->lock, flags);
 
 		enable_irq_wake(bp->queues[0].irq);
 	}
@@ -6065,6 +6067,8 @@ static int __maybe_unused macb_resume(struct device *dev)
 		queue_readl(bp->queues, ISR);
 		if (bp->caps & MACB_CAPS_ISR_CLEAR_ON_WRITE)
 			queue_writel(bp->queues, ISR, -1);
+		spin_unlock_irqrestore(&bp->lock, flags);
+
 		/* Replace interrupt handler on queue 0 */
 		devm_free_irq(dev, bp->queues[0].irq, bp->queues);
 		err = devm_request_irq(dev, bp->queues[0].irq, macb_interrupt,
@@ -6073,10 +6077,8 @@ static int __maybe_unused macb_resume(struct device *dev)
 			dev_err(dev,
 				"Unable to request IRQ %d (error %d)\n",
 				bp->queues[0].irq, err);
-			spin_unlock_irqrestore(&bp->lock, flags);
 			return err;
 		}
-		spin_unlock_irqrestore(&bp->lock, flags);
 
 		disable_irq_wake(bp->queues[0].irq);
 

-- 
2.53.0

[PATCH net v2 2/2] net: macb: Protect access to net_device::ip_ptr with RCU lock

[Kevin Hao]

Access to net_device::ip_ptr and its associated members must be
protected by an RCU lock. Since we are modifying this piece of code,
let's also move it to execute only when WAKE_ARP is enabled.

To minimize the duration of the RCU lock, a local variable is used to
temporarily store the IP address. This change resolves the following
RCU check warning:
  WARNING: suspicious RCU usage
  7.0.0-rc3-next-20260310-yocto-standard+ #122 Not tainted
  -----------------------------
  drivers/net/ethernet/cadence/macb_main.c:5944 suspicious rcu_dereference_check() usage!

  other info that might help us debug this:

  rcu_scheduler_active = 2, debug_locks = 1
  5 locks held by rtcwake/518:
   #0: ffff000803ab1408 (sb_writers#5){.+.+}-{0:0}, at: vfs_write+0xf8/0x368
   #1: ffff0008090bf088 (&of->mutex#2){+.+.}-{4:4}, at: kernfs_fop_write_iter+0xbc/0x1c8
   #2: ffff00080098d588 (kn->active#70){.+.+}-{0:0}, at: kernfs_fop_write_iter+0xcc/0x1c8
   #3: ffff800081c84888 (system_transition_mutex){+.+.}-{4:4}, at: pm_suspend+0x1ec/0x290
   #4: ffff0008009ba0f8 (&dev->mutex){....}-{4:4}, at: device_suspend+0x118/0x4f0

  stack backtrace:
  CPU: 3 UID: 0 PID: 518 Comm: rtcwake Not tainted 7.0.0-rc3-next-20260310-yocto-standard+ #122 PREEMPT
  Hardware name: ZynqMP ZCU102 Rev1.1 (DT)
  Call trace:
   show_stack+0x24/0x38 (C)
   __dump_stack+0x28/0x38
   dump_stack_lvl+0x64/0x88
   dump_stack+0x18/0x24
   lockdep_rcu_suspicious+0x134/0x1d8
   macb_suspend+0xd8/0x4c0
   device_suspend+0x218/0x4f0
   dpm_suspend+0x244/0x3a0
   dpm_suspend_start+0x50/0x78
   suspend_devices_and_enter+0xec/0x560
   pm_suspend+0x194/0x290
   state_store+0x110/0x158
   kobj_attr_store+0x1c/0x30
   sysfs_kf_write+0xa8/0xd0
   kernfs_fop_write_iter+0x11c/0x1c8
   vfs_write+0x248/0x368
   ksys_write+0x7c/0xf8
   __arm64_sys_write+0x28/0x40
   invoke_syscall+0x4c/0xe8
   el0_svc_common+0x98/0xf0
   do_el0_svc+0x28/0x40
   el0_svc+0x54/0x1e0
   el0t_64_sync_handler+0x84/0x130
   el0t_64_sync+0x198/0x1a0

Fixes: 0cb8de39a776 ("net: macb: Add ARP support to WOL")
Signed-off-by: Kevin Hao <haokexin@gmail.com>
Cc: stable@vger.kernel.org
---
 drivers/net/ethernet/cadence/macb_main.c | 25 ++++++++++++++++---------
 1 file changed, 16 insertions(+), 9 deletions(-)

diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
index 2d4304331e297accd91ab48813a9bd4722ce72dc..9856764402b17397928d0a61da61865a3b10484f 100644
--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c
@@ -5909,9 +5909,9 @@ static int __maybe_unused macb_suspend(struct device *dev)
 	struct macb_queue *queue;
 	struct in_device *idev;
 	unsigned long flags;
+	u32 tmp, ifa_local;
 	unsigned int q;
 	int err;
-	u32 tmp;
 
 	if (!device_may_wakeup(&bp->dev->dev))
 		phy_exit(bp->phy);
@@ -5920,14 +5920,21 @@ static int __maybe_unused macb_suspend(struct device *dev)
 		return 0;
 
 	if (bp->wol & MACB_WOL_ENABLED) {
-		/* Check for IP address in WOL ARP mode */
-		idev = __in_dev_get_rcu(bp->dev);
-		if (idev)
-			ifa = rcu_dereference(idev->ifa_list);
-		if ((bp->wolopts & WAKE_ARP) && !ifa) {
-			netdev_err(netdev, "IP address not assigned as required by WoL walk ARP\n");
-			return -EOPNOTSUPP;
+		if (bp->wolopts & WAKE_ARP) {
+			/* Check for IP address in WOL ARP mode */
+			rcu_read_lock();
+			idev = __in_dev_get_rcu(bp->dev);
+			if (idev)
+				ifa = rcu_dereference(idev->ifa_list);
+			if (!ifa) {
+				rcu_read_unlock();
+				netdev_err(netdev, "IP address not assigned as required by WoL walk ARP\n");
+				return -EOPNOTSUPP;
+			}
+			ifa_local = be32_to_cpu(ifa->ifa_local);
+			rcu_read_unlock();
 		}
+
 		spin_lock_irqsave(&bp->lock, flags);
 
 		/* Disable Tx and Rx engines before  disabling the queues,
@@ -5966,7 +5973,7 @@ static int __maybe_unused macb_suspend(struct device *dev)
 		if (bp->wolopts & WAKE_ARP) {
 			tmp |= MACB_BIT(ARP);
 			/* write IP address into register */
-			tmp |= MACB_BFEXT(IP, be32_to_cpu(ifa->ifa_local));
+			tmp |= MACB_BFEXT(IP, ifa_local);
 		}
 		spin_unlock_irqrestore(&bp->lock, flags);
 

-- 
2.53.0

Re: [PATCH net v2 2/2] net: macb: Protect access to net_device::ip_ptr with RCU lock

[Théo Lebrun]

Hello Kevin,

On Wed Mar 18, 2026 at 7:36 AM CET, Kevin Hao wrote:
> Access to net_device::ip_ptr and its associated members must be
> protected by an RCU lock. Since we are modifying this piece of code,
> let's also move it to execute only when WAKE_ARP is enabled.
>
> To minimize the duration of the RCU lock, a local variable is used to
> temporarily store the IP address. This change resolves the following
> RCU check warning:
>   WARNING: suspicious RCU usage
>   7.0.0-rc3-next-20260310-yocto-standard+ #122 Not tainted
>   -----------------------------
>   drivers/net/ethernet/cadence/macb_main.c:5944 suspicious rcu_dereference_check() usage!
>
>   other info that might help us debug this:
>
>   rcu_scheduler_active = 2, debug_locks = 1
>   5 locks held by rtcwake/518:
>    #0: ffff000803ab1408 (sb_writers#5){.+.+}-{0:0}, at: vfs_write+0xf8/0x368
>    #1: ffff0008090bf088 (&of->mutex#2){+.+.}-{4:4}, at: kernfs_fop_write_iter+0xbc/0x1c8
>    #2: ffff00080098d588 (kn->active#70){.+.+}-{0:0}, at: kernfs_fop_write_iter+0xcc/0x1c8
>    #3: ffff800081c84888 (system_transition_mutex){+.+.}-{4:4}, at: pm_suspend+0x1ec/0x290
>    #4: ffff0008009ba0f8 (&dev->mutex){....}-{4:4}, at: device_suspend+0x118/0x4f0
>
>   stack backtrace:
>   CPU: 3 UID: 0 PID: 518 Comm: rtcwake Not tainted 7.0.0-rc3-next-20260310-yocto-standard+ #122 PREEMPT
>   Hardware name: ZynqMP ZCU102 Rev1.1 (DT)
>   Call trace:
>    show_stack+0x24/0x38 (C)
>    __dump_stack+0x28/0x38
>    dump_stack_lvl+0x64/0x88
>    dump_stack+0x18/0x24
>    lockdep_rcu_suspicious+0x134/0x1d8
>    macb_suspend+0xd8/0x4c0
>    device_suspend+0x218/0x4f0
>    dpm_suspend+0x244/0x3a0
>    dpm_suspend_start+0x50/0x78
>    suspend_devices_and_enter+0xec/0x560
>    pm_suspend+0x194/0x290
>    state_store+0x110/0x158
>    kobj_attr_store+0x1c/0x30
>    sysfs_kf_write+0xa8/0xd0
>    kernfs_fop_write_iter+0x11c/0x1c8
>    vfs_write+0x248/0x368
>    ksys_write+0x7c/0xf8
>    __arm64_sys_write+0x28/0x40
>    invoke_syscall+0x4c/0xe8
>    el0_svc_common+0x98/0xf0
>    do_el0_svc+0x28/0x40
>    el0_svc+0x54/0x1e0
>    el0t_64_sync_handler+0x84/0x130
>    el0t_64_sync+0x198/0x1a0
>
> Fixes: 0cb8de39a776 ("net: macb: Add ARP support to WOL")
> Signed-off-by: Kevin Hao <haokexin@gmail.com>
> Cc: stable@vger.kernel.org
> ---
>  drivers/net/ethernet/cadence/macb_main.c | 25 ++++++++++++++++---------
>  1 file changed, 16 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
> index 2d4304331e297accd91ab48813a9bd4722ce72dc..9856764402b17397928d0a61da61865a3b10484f 100644
> --- a/drivers/net/ethernet/cadence/macb_main.c
> +++ b/drivers/net/ethernet/cadence/macb_main.c
> @@ -5909,9 +5909,9 @@ static int __maybe_unused macb_suspend(struct device *dev)
>  	struct macb_queue *queue;
>  	struct in_device *idev;
>  	unsigned long flags;
> +	u32 tmp, ifa_local;
>  	unsigned int q;
>  	int err;
> -	u32 tmp;
>  
>  	if (!device_may_wakeup(&bp->dev->dev))
>  		phy_exit(bp->phy);
> @@ -5920,14 +5920,21 @@ static int __maybe_unused macb_suspend(struct device *dev)
>  		return 0;
>  
>  	if (bp->wol & MACB_WOL_ENABLED) {
> -		/* Check for IP address in WOL ARP mode */
> -		idev = __in_dev_get_rcu(bp->dev);
> -		if (idev)
> -			ifa = rcu_dereference(idev->ifa_list);
> -		if ((bp->wolopts & WAKE_ARP) && !ifa) {
> -			netdev_err(netdev, "IP address not assigned as required by WoL walk ARP\n");
> -			return -EOPNOTSUPP;
> +		if (bp->wolopts & WAKE_ARP) {
> +			/* Check for IP address in WOL ARP mode */
> +			rcu_read_lock();
> +			idev = __in_dev_get_rcu(bp->dev);
> +			if (idev)
> +				ifa = rcu_dereference(idev->ifa_list);
> +			if (!ifa) {
> +				rcu_read_unlock();
> +				netdev_err(netdev, "IP address not assigned as required by WoL walk ARP\n");
> +				return -EOPNOTSUPP;
> +			}
> +			ifa_local = be32_to_cpu(ifa->ifa_local);
> +			rcu_read_unlock();
>  		}
> +
>  		spin_lock_irqsave(&bp->lock, flags);
>  
>  		/* Disable Tx and Rx engines before  disabling the queues,
> @@ -5966,7 +5973,7 @@ static int __maybe_unused macb_suspend(struct device *dev)
>  		if (bp->wolopts & WAKE_ARP) {
>  			tmp |= MACB_BIT(ARP);
>  			/* write IP address into register */
> -			tmp |= MACB_BFEXT(IP, be32_to_cpu(ifa->ifa_local));
> +			tmp |= MACB_BFEXT(IP, ifa_local);
>  		}
>  		spin_unlock_irqrestore(&bp->lock, flags);
>  

Even better to guard the RCU critical section inside a
`if (bp->wolopts & WAKE_ARP)` block.

Reviewed-by: Théo Lebrun <theo.lebrun@bootlin.com>

Thanks,

--
Théo Lebrun, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

Re: [PATCH net v2 0/2] net: macb: Fix two lock warnings when WOL is used

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Wed, 18 Mar 2026 14:36:57 +0800 you wrote:
> Hi,
> 
> This patch series addresses two lock warnings that occur when using WOL as a
> wakeup source on my AMD ZynqMP board.
> 
> ---
> Cc: Nicolas Ferre <nicolas.ferre@microchip.com>
> Cc: Claudiu Beznea <claudiu.beznea@tuxon.dev>
> Cc: Andrew Lunn <andrew+netdev@lunn.ch>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: Eric Dumazet <edumazet@google.com>
> Cc: Jakub Kicinski <kuba@kernel.org>
> Cc: Paolo Abeni <pabeni@redhat.com>
> Cc: Vineeth Karumanchi <vineeth.karumanchi@amd.com>
> Cc: Harini Katakam <harini.katakam@amd.com>
> Cc: Théo Lebrun <theo.lebrun@bootlin.com>
> 
> [...]

Here is the summary with links:
  - [net,v2,1/2] net: macb: Move devm_{free,request}_irq() out of spin lock area
    https://git.kernel.org/netdev/net/c/317e49358ebb
  - [net,v2,2/2] net: macb: Protect access to net_device::ip_ptr with RCU lock
    https://git.kernel.org/netdev/net/c/baa35a698cea

You are awesome, thank you!
-- 
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